Method of removing lead from nickel



Patented Jan. 20, 1925.

UNITED STATES PATENT OFFICE.

NOAK VICTOR HYBINETTE, OF WILMINGTON, DELAWARE, ASSIG-NOR TO NATIONAL TRUST COMPANY, LIMITED, 013 TORONTO, CANADA.

METHOD OF REMOVING LEAD FROM NICKEL.

No Drawing.

To all whom it may concern:

Be it known that I, NoAK VICTOR Hrnmnr'rn, a subject of the King of Norway, residing temporarily at Wilmington, in the county of New Castle, State of Delaware, have invented certain new and useful Improvements in Methods of Removing Lead from Nickel; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to the removal of lead from nickel, and particularly to the separation of relatively minute quantities-of lead which affect the malleability of the nickel and of alloys thereof.

It is generally understood that electrolytic nickel contains certain proportions of lead, but owing to the inaccuracy of analytical methods the proportion of lead which is present in nickel has not been appreciated heretofore. It has also not been appreciated that the presence of lead materially aifects the malleability of nickel and .of alloys thereof when lead is present in quantities exceeding 0.02 per cent. The effect is especially marked in the case of nickel steel or alloys containing over 30 per cent of nickel.

It is understood that lead may-be removed from nickel or from alloys thereof by heating the molten metal to a temperature above its melting point. This method is successful only in the partial removal of the lead so that th final product still contains from 0.04 to 0.06 per cent of lead. As noted, this is sufficient to decrease the malleability of the product and is therefore considered detrimental to the product.

It is the object of the present invention to provide a method whereby substantially all of the lead may be separated from nickel in an economical and efficient manner, and T have discovered that this result may be accomplished by the violent agitation of the metal while in a highly heated condition. The agitation may be accomplished by chemical or physical means, but the heating is preferably internal as the result of oxida tion of added material.

That the two conditions mentioned are essential to the successful accomplishment of the object is apparent from the fact that the removal of the lead is not accomplished by oxidation of the molten nickel in the Application filed September 26, 1922. Serial No. 590,671.

thermore, the introduction of carbon to the oxidized bath will not result in removal of the lead even though the poling operation results in violent agitation of the bath.

The result may be successfully accomplished, however, by the addition of an oxidizable material such as aluminum, silicon, zinc or the like to the bath and the subsequent oxidation of the bath. for example, by the introduction of an air blast. Similarly, although less advai'itageously. carbonization of the bath followed by oxidation will remove lead therefrom. T ascribe the result observed to the internal heating of the bath by oxidation of the added oxidizable material although it is by no means certain that this explanation fully accounts for the phenomenon. The added material may be me tallic aluminum, which is preferred, silicon in the form of nickel-silicide or any other oxidizable condition, metallic zinc, or combinations of these materials with each other or with other similar materials.

In carrying out the invention I preferably proceed as. follows: The nickel to be purified is melted under oxidizing or carbonizing conditions in a reverberatory furnace and is oxidized in any suitable manner as by the addition of nickel oxide or by the use of an air blast or simply by the oxidizing flame. Thel slag is wholly or partly removed and a fr action of 1 per cent of aluminum, for example, is added. The molten bath is then again oxidized preferably by an air blast and the resulting violent action agitates the bath. At the conclusion of the operation the lead is found to be substantially or wholly removed. It is probable that the lead is oxidized and volatilized, passing from the bath as fume.

The operation may be repeated if necessary until all traces of lead have been separated. In some cases it may be unnecessary to remove all of the lead, in which event one or more refining operations as herein described may be conducted to remove the lead to the desired maximum content.

Addition of a basic slag, such as a mixture of lime with fluorspar or calcium chloride, to the molten metal seems to be beneficial.

The method may, however, be conducted successfully without the addition of such slag which is not essential to the removal of the lead.

From the foregoing it will appear that I have provided a method of separating relatively minute quantities of lead fromnickel and am: able, therefore, to produc an improved nickel which exhibits all of he characteristic and desirable properties of that metal. The influence of the lead upon the malleability of the nickel and of alloys thereof is obviated by the removal of the lead as described. The lead-free nickel has numerous uses, therefore, to which ordinary electrolytic nickel is not well adapted because of its lack of malleability.

Various changes may be made in the details of the operation within the scope of the accompanying claims and without departing from the invention or sacrificing the advantages thereof.

' I claim :fv

l. The method of removing lead from nickel, comprising smelting the nickel or alloy thereof, addmg an oxidizable material thereto and oxidizing the molten bath toremove substantially all the added oxidizable material and the lead.

2. The method of removing lead from nickel, comprising smelting the nickel or alloy thereof, adding aluminum thereto and oxidizing the molten bath.

3. The method of removing lead from nickel, comprising smelting the nickel or alloy thereof, addlng an oxidizable material thereto and oxidizing the molten bath by the introduction of an air blast which agitates the metal.

4. The method of removing lead from nickel, which comprises internally heating a molten bath of the nickel or alloys thereof by the oxidation therein of an added mate:

rial accompanied by agitation of the bath.

5. The method of removing lead from nickel, which comprises internally heating a molten bath of the nickel or alloys thereof successively, the successive heatings being accomplished by the oxidation in the bath of added material.

In testimony whereof I afiix my signature.

NOAK VICTOR HYBINETTE. 

